Adam Back is a British cryptographer and cypherpunk. He is an inventor of Hashcash - a proof-of-work system used to limit email spam and denial-of-service attacks, and more recently has become known for its use in bitcoin (and other cryptocurrencies) as part of the mining algorithm.
Adam is also the CEO of blockchain technology company - Blockstream.
Back was one of the first two people to receive an email from Satoshi Nakamoto. In 2016, the Financial Times cited Back as a potential Nakamoto candidate, along with Nick Szabo and Hal Finney. Charles Hoskinson, founder of Cardano, stated that Adam Back is the most likely Satoshi Nakamoto candidate.